Aqueous release coating compositions have been used for many years for application to various substrates, whereby various materials may be placed in adhering contact with such release-coated substrates but wherein such various materials may be easily and quickly released and removed from such release-coated substrates at a subsequent time.
Release coating compositions commonly in present commercial and industrial use contain conventional release agents, such as a silicone polymer, or a stearate chromium complex, or other relatively expensive materials, or other relatively less expensive release agents, such as polyvinyl alcohol.
However, even polyvinyl alcohol is relatively expensive, as compared to other commercial materials and, particularly in those applications where the polyvinyl alcohol is applied to a more or less porous substrate and is undesirably absorbed thereinto, it is desired that either the concentration of the polyvinyl alcohol in the release coating composition be reduced to an absolute minimum, or that measures be taken to reduce the undesirable absorption of the polyvinyl alcohol into the more or less porous substrate.
Of course, the substrate could be initially pre-treated with a primer coating or sealing compound, such as a thin layer of a relatively hard wax, or similar material, which would materially prevent the polyvinyl alcohol from undesirably soaking into the substrate, but such practice does not markedly reduce the materials-cost factor involved and actually in many instances increases the overall production-cost factor by the introduction of an additional processing step in the overall manufacturing cycle.